This invention relates generally to apparatus for the non-invasive, real-time nuclear magnetic resonance (NMR) spectroscopy and video imaging of materials and is particularly directed to in situ measurement of electrochemical properties of an electrolytic material using a modified toroid cavity detector (TCD), a video detector, and an arrangement for the acquisition of the NMR and video data.
Spectroscopic tools such as nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), electron paramagnetic resonance (EPR), and ultraviolet/visible spectroscopy (UVNIS) provide insight into the atomic connectivities, architecture, dynamics, and electronic multiplicity in molecules. The data that these tools generate is in the form of spectrographs, which are signatures of the electronic structure that binds atoms together to form molecules. Spectrographs are interpreted using models, compared to standards, and simulated by ab initio calculations to reveal or corroborate atomic structure in molecules. Spectroscopic tools operate at a molecular level to analyze bulk materials that are typically in an isotropic powder or liquid form. Crystalline and lamellar materials exhibit long-range order in one or more spatial dimensions when crystallized from solution or cooled from a melt. Several spectroscopic and imaging devices have examined molecular aggregation during the formation of long-range microscopic order in a sample. Gravitational, magnetic, and electric fields have been used to influence the direction of molecular aggregation. The patterns in NMR spectrographs change according to the orientation that a sample with long-range order has in the applied external magnetic field. A device that can simultaneously photograph microscopic molecular aggregation under the influence of a force field (and variable conditions of temperature and pressure) and record spectroscopic information in situ would establish a direct, unambiguous connection between spectrographic and image data of long-range molecular order. One of these types of devices is a video toroid cavity imager which operates in the presence of a large applied magnetic field, under controlled temperature and pressure, to provide simultaneous NMR spectroscopy and video imaging capabilities for investigating the evolution of long-range molecular aggregation. In the new nanotechnology field, the video toroid cavity imager can play an important role in characterizing and investigating the formation and properties of macroscopic thin films that are organized on the molecular level.
An earlier apparatus employing NMR imaging to provide in situ measurements of electrochemical properties of a sample and including a cylindrical toroid cavity resonator is disclosed in U.S. Pat. No. 6,046,592 to Rathke et al. This apparatus includes a cylindrical electrochemical cell 32 disposed within a sealed toroid cavity resonator 12 constructed from a material having a good electrical conductivity. A metal rod defines the axis of the cylindrical device and serves as the working electrode of the cell and the central conductor of the toroid cavity NMR detector. A glass tube surrounds the central conductor and contains the sample. A helical coil is disposed within the glass tube and is used as a counter electrode. Attached in a threaded manner to one end of the toroid cavity resonator 12 is a toroid cavity end cap 26 having a single compression fitting 28 which serves to pass the working electrode 20 from a NMR spectrometer 44 through the toroid cavity end cap 26 to the base 31 of the electrochemical cell compartment 32. Two compression fittings 16 and 18 on the opposed end of the toroid cavity 12 serve to pass electrodes 20 and 22 to a potentiostat 42 for charging the electrodes as shown in FIG. 2. The geometry of this arrangement is limiting in terms of making measurements of the flat circular components of a coin cell battery.
Another approach to the design of a toroid cavity detector for NMR analyses is disclosed in U.S. Pat. No. 6,469,507 to Gerald II et al. This imaging apparatus offers the advantage of maintaining the sample adjacent to or in contact with a principle detector element 238 which is in the form of flat metal conductor, the plane of which is parallel to the longitudinal axis of the toroid cavity 42. This arrangement is convenient because flat anode laminates, polymer electrolyte films, and cathode laminates are routinely prepared, and can be easily stacked and compressed to facilitate their incorporation and use in this apparatus for analyzing coin cells using wide line multinuclear-NMR spectroscopy and imaging. The sample is subjected to NMR analyses when a static main homogenous magnetic field (B0) produced by a NMR magnetic device is applied to the toroid cavity 42 and a radio frequency (RF) excitation signal pulse is provided to the principle detector element 238 so that an alternately energized and de-energized magnetic field (B1) is produced in the sample and throughout the toroid cavity.
The present invention addresses the aforementioned limitations of the prior art by providing a toroid cavity detector for use in NMR analyses of a sample which provides recorded video images of the sample.
Accordingly, it is an object of the present invention to provide apparatus for simultaneously photographing microscopic molecular aggregation under the influence of a force field while recording spectroscopic information in situ to determine the relationship between image and spectroscopic data of long-range molecular order.
It is another object of the present invention to provide apparatus for investigating and characterizing the formation and properties of macroscopic thin films that are organized on the molecular level.
A further object of the present invention is to provide for the real-time in situ spectral analyses of the electronic structure that binds atoms together to form molecules and optical analyses of microscopic molecular aggregation of materials under the influence of a force field during the formation of long-range molecular order.
A still further object of the present invention is to provide an improved compression coin cell battery imager for the in situ electrochemical analyses and evaluation of the electrodes of a sealed battery using NMR and optical techniques.
This invention contemplates a toroid cavity detector cell for in situ analyses of a sample through the use of nuclear magnetic resonance, wherein the sample includes plural stacked components, the toroid cavity detector cell comprising: a housing having a cylindrical recessed portion therein; a removable cover plate attached to the housing and disposed over the cylindrical recessed portion to form a closed toroid cavity; a detector disposed in the closed toroid cavity and containing the sample, as well as an electrolyte; a piston arrangement attached to the cover plate for applying increased pressure on the detector cell for ensuring mechanical contact between the stacked components in the sample, hermetically sealing the electrolyte and sample within the detector cell, and uniform application of the magnetic field to the plural stacked components in the sample.
The present invention is further directed to a toroid cavity apparatus for in situ analyses of a sample through the use of nuclear magnetic resonance and optical inspection, the toroid cavity apparatus comprising: a closed housing forming a toroid cavity, wherein the housing is disposed in an externally applied magnetic field B0, and contains a sample to be analyzed; a detector cell disposed within the toroid cavity containing the sample; an NMR spectrometer electrically coupled to the detector cell for producing an alternately energized and de-energized magnetic filed B1 through the toroid cavity and within the sample for the spectroscopic analyses of the sample; a laser or incandescent light source coupled to the toroid cavity for directing laser or white light, respectively, onto the sample; and a video camera coupled to the toroid cavity and focused on the sample for viewing and recording the appearance of the sample.